An engine and a battery are mounted on an automobile, and the battery is charged using power from the engine. Conventionally, as charge control that is performed to charge a battery, a technology to reduce the charge to the battery to reduce fuel consumption during normal running and to charge the battery by regenerative electric power generation during deceleration is known.
As control that reduces fuel consumption, idling stop (also referred to as idle reduction) control is known. In Patent Literature 1 below, an automobile is disclosed that is provided with both a charge control function and an idling stop control function to meet a demand for improving fuel efficiency.
In the above technology, however, when the amount of electric power that is stored in the battery is consumed by auxiliary machines while the engine is kept stopped by idling stop control, the engine may be restarted because of a shortage of SOC (State of Charge). The “SOC” is an index that represents how much electric power remains in a battery. Especially, in the above technology, engine restart due to a shortage of SOC is likely to occur because the surplus SOC is decreased by the charge control function. Thus, the fuel efficiency cannot be sufficiently improved and there is a room for improvement.